Correspondence

摘要

Mariners who attended advanced shiphandling courses or have been doing a little bit of digging in books treating ship behavior have some knowledge of the term "added mass." Simply put, the added mass is a quantity of water that the ship carries along with her when she has headway or sternway. If you have to stop a ship of 40,000 tons displacement, the astern-moving propeller must work overtime to overcome the ship's inertia plus two volumes of water: the volume ahead that wants to keep going and attracts the bow in a partial vacuum; and the volume astern, the following fill-in flow racing forward towards the poop.